Periodontium Flashcards

ILO 8.5b: have knowledge in the form and function of teeth, and the oral environment, in health and disease

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1
Q

what are the roles of the periodontium?

4

A

tissue that supports and surrounds teeth
retains tooth in socket
resists masticatory loads
defensive barrier against threats from oral environment

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2
Q

what is the junctional epithelium?

A

physical barrier separating the body tissues from the oral environment

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3
Q

what are periodontal diseases divided into?

2

A

diseases of the gingiva
diseases of all periodontal tissues

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4
Q

what are the properties of cementum?

4

A

covers root dentine
very similar structure to bone
provides attachment for some periodontal fibres
laid down by cementocytes

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5
Q

what is the difference between acellular and cellular cementum?

5, 7

A

acellular
* no cells
* usually adjacent to dentine
* formed first - primary cementum
* cervical 2/3 of root
* Sharpey’s fibres from PDL
cellular
* contains cementocytes
* formed later - secondary cementum
* apical 1/3 of root and furnication regions
* no Sharpey’s fibres
* fibres parallel to surface
* no role in tooth attachment
* may represent a transitional form

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6
Q

what are the alternate classification names for acellular and cellular cementum?

2

A

acellular - acellular extrinsic fibre cementum
cellular - cellular intrinsic fibre cementum

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7
Q

describe the structure of alveolar bone

4

A

similar to bone elsewhere in body
‘cortical’ plate forms inner lining of tooth socket
penetrated by nutrient canals
inner ‘cancellous’ bone contains bone marrow

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8
Q

what is the function of alveolar bone?

2

A

provides attachment for periodontal ligament fibres - Sharpey’s fibres
supports the teeth

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9
Q

what happens to alveolar bone when teeth are lost?

1

A

alveolar process is reabsorbed, leaving a ‘residual ridge’

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10
Q

what does the periodontal ligament contain?

5

A

cells
extracellular matrix
fibres
nerves
blood vessels

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11
Q

what does the periodontal ligament matrix contain?

3

A

hylauronate GAGs
glycoproteins - fibroconectin
proteoglycans

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12
Q

what cells are present in the periodontal ligament?

5

A

fibroblasts
cementoblasts
osteoclasts and cementoclasts
epithelial cells
defence cells

cell rests of Malassez = epithelial cell cluster reminants of Hertwigs epithelial root sheath (HERS)

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13
Q

what kinds of nerves are present in the periodontal ligament?

2 (2,1)

A

sensory
* mechanoreceptors
* nociceptors
autonomic (sympathetic)

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14
Q

where does the blood supply to the periodontal ligament come from?

2

passes in to PDL? gingiva supply?

A

inferior and superior arteries passing into PDL
lingual and palatine arteries supply gingiva

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15
Q

what are the two types of periodontal ligament fibre and what do they do?

2

A

true periodontal ligament - attach tooth to bone at or apical to alveolar crest
gingival ligament - fibres above the alveolar crest

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16
Q

what are the periodontal ligament fibres made up from?

3

A

collagen (type 1 ands 3)
oxytalan fibres
elastic fibres (not in humans)

17
Q

what are the two periodontal fibre groups and what fibres do they contain?

2 (5,1)

A

alveolo-dental fibres
* alveolar
* horizontal
* oblique
* apical
* interradicular (multi-rooted teeth)
interdental ligament
* transseptal fibres

18
Q

describe how the alveolar and oblique fibres attach to bone and cementum

A

alveolar fibres attach to bone apically and cementum cercivally
oblique fibres attach to bone cervically and cementum apically

19
Q

what does the gingival ligament fibre group do and where is it present?

2

A

support the free gingivae
present at lamina propria in marginal gingiva

20
Q

what types of gingival ligament fibres are there?

4

A

dento-gingival
alveolo-gingival
dento-periosteal
circular

21
Q

describe the dento-gingival junction

A
22
Q

where is the junctional epithelium found and how are they attached to the enamel?

3

A

found at the base of the gingival sulcus until the CEJ
hemidesmosomes attach epithelia to the basal lamina next to enamel
desmosomes attach each epithelial cell together

23
Q

where is the interdental col and what is it prone to?

2

A

gingival tissue below the contact point of adjacent teeth
prone to plaque build up due to concave shape and non-keratinised stratified squamous epithelium

24
Q

what intrusive forces are the periodontal ligament and teeth exposed to?

4,2

A

PDL: mastication, swallowing, speech, parafunction (clenching, grinding)
teeth: sticky foods, orthodontic forces

25
Q

what is the effect of periodontal ligament loading?

4

A

initial elastic component
later, viscous ‘creep’
tension in PDL fibres
compression of ECF